Function CurrentScreen

CurrentScreen(): ReactNode
Render the current screen, overlays, and modals.

Multiple overlays are rendered in zIndex order (ascending) so higher zIndex overlays appear on top. Each overlay is wrapped in a LayerElementContext.Provider so the keyboard system can isolate per-overlay keyboard layers by overlay ID.

Modals are rendered after overlays so they always appear visually on top. Each modal is wrapped in a ModalLayerElementContext.Provider so the keyboard system can isolate per-modal keyboard layers by modal ID.

Architecturally symmetric between overlays and modals.

Returns ReactNode
Example
Render it as the leaf of the provider chain:
```
<ScenarioManagementProvider defaultScreen={MainScreen} fullScreen>
  <KeyboardProvider modes={['normal', 'insert']} mouse>
    <CurrentScreen />
  </KeyboardProvider>
</ScenarioManagementProvider>
```
- Defined in screen/current-screen.tsx:31